The undulation pump ventricular assist device (UPVAD) is a small implantable VAD. The UPVAD can pro-duce arbitrary flow patterns: continuous flow, partial pulsatile flow and complete pulsatile flow, by changing the motor rotational speed of the UPVAD. For the pulsatile flow, the timing of the UPVAD operation has to be synchronized with the natural heartbeat to prevent the sucking of inflow cannula. The purpose of this study is to develop the control method of heartbeat synchronization for the UPVAD. The inflow cannula of the UPVAD is implanted into the ventricle. Pressure fluctuation that synchronizes with the natural heartbeat is observed in the inflow cannula. By changing the motor rotational speed synchronously with the inflow pressure, the UPVAD can synchronize with the natural heartbeat and the UPVAD can generate a co-pulse assist flow. The UPVAD generated 5.3 l/min co-pulse assist flow without inflow cannula sucking using this control method. The pulsatile assist flow can be increased more than 15%. The UPVAD can generate the suitable assist flow with the developed control method.